Telephone-exchange system



A. RAYNSFORD. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED 050.111.1919.

T0 OPE 1717 5 lnven for: Arfhur Rayn f by WAY Patented Jan. 17, 1922.

UNITED STATES PATENT OFFICE.

ARTHUR RAYNSFORD, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Jan. 17, 1922.

Application filed December 31, 1919. Serial No. 348,512.

To all whom it may concern:

Be it known that I, ARTHUR RAYNSFORD, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and exact descrlption.

This invention relates to telephone exchange systems and more particularly to such systems in which connection is to be established between a telephone line terminating in a manual exchange and a telephone line terminating at an automatic exchange.

The principal feature of the invention resides in the provision of means for preventing the false operation of automatic switching apparatus at the automatic exchange end of the trunk circuit when connection is made therewith at the manual exchange.

Other features which result from or are incident to the main object above noted will appear during the description of the invention.

One embodiment of this invention is illus trated in the accompanying drawing which shows a telephone line A terminating at a manual exchange in a jack 7 and a linesignal 6. At the manual exchange there is shown a cord circuit B which may be employed to connect the telephone line A with a trunk circuit C extending from the manual exchange to an automatic exchange where it may connect with an automatic telephone line G terminating at the automatic exchange. The apparatus shown to the left of the dotted line OO is located at the manual exchange while that shown to the right thereof is located at the automatic exchange. Switching apparatus comprising a line finder D, a selector E and a connector F is schematically shown as part of the automatic switching apparatus and may be of any well. known type in which the switches are controlled over a loop circuit. There are shown at the operators position in the manual exchange a sender S, a

relay 33 and a relay 35 which may be com mon to a plurality of cord circuits, such as B at an operators position.

It is thought that the invention may be more fully comprehended from the followmg description of the operation of the system shown on the drawin Assuming that station A originates a call, li hting the line signal 6 in the usual manner in response to the operation of line relay 5, the operator in answering the call, inserts plug 8 of the cord circuit B into the jack 7, thereby disconnecting the line relay 5 and extinguishing the line signal 6. Insertion of plug 8 into jack 7 completes a circuit for supervisory lamp 21 of the circuit B, said circuit extending from ground,

sleeves of jack 7 and plug 8, to supervisory signal 21, to armature and back contact of relay 20, and through resistance 22 to grounded battery. The operator then actuates listening key 9 and non-locking key 15 associated with her telephone set, and inquires the wants of the calling subscriber at station A and upon being informed that connection is desired with the line of subscriber G terminating at the automatic exchange. the operator releases key 15 and restores listening key 9 to normal. It will be noted that in actuating non-locking key 15, a circuit was completed from ground, through the upper contacts of key 15. upper winding of retardation coil 16, left-hand contact of listening key 9, upper normal contacts of ringing key 4:, tips of plug 8 and jack 7, through the sub-station loop, rings of jack 7 and plug 8, lower normal contacts of ringing key 4, winding of relay 20, inner right-hand contacts of listening key 9, lower winding of retardation coil 16, lower contacts of non-locking key 15 to grounded battery. This circuit supplies current for talking purposes to the calling subscriber at station A and also serves to energize supervisory relay 20, which upon attracting its armature opens the circuit for supervisory signal 21. The operator then inserts calling plug 30 into jack 31 of an idle trunk C extending to the automatic exchange, whereupon sleeve relay 32 of the trunk circuit is energized over a circuit extending from grounded battery, through rethe manner well known.

sistance 29, sleeves of plug 30 and jack 31, and the winding of relay 32 to ground.

The operator then actuates the dialing key 24, thereby completing a circuit through its upper contacts for relay 25. Relay 25 in operating disconnects the answering end of the cord circuit B from the calling end and connects impulse sender S to the calling end. Relay 25 in operating connects vround and battery to the tip and ring conuctors respectively of the answering end of the cord circuit, thereby maintaining supervisory relay 2O energized and superyisory signal 21 extinguished during dialmg. p

The resistances 26 and 27 serve to prevent clicks in the receiver of the calling subseriber when relay 25 is (lo-energized and the calling line is extended through to the automatic exchange.

p The operator then actuates impulse sender ,S whereupon relay 33 associated with the sender and relay 39 of the trunk circuit are energized over a circuit extending from grounded battery, through the left-hand winding of relay 33, normal contacts of relay 35, off-normal contacts 50 of impulse sender S, closed upon the initial movement of the sender, inner armature and alternate contact of relay 25, rings of plug 30 and jack 31, left-hand normal contacts of relay 39, and winding of relay 39 to ground. .Re-

lay 39 thereupon locks up under control of the sleeve relay 32 over a circuit extending from ground, through the left-hand winding of relay 39, left-hand alternate contacts of relay 39, alternate'contacts of relay 32 to grounded battery. Relay 33 looks up under control of key 24 over a circuit including grounded battery, left-hand and right-hand windings of relay 33, front con tact and inner armature of relay 33, and lower contacts of key 24 to ground. Relay 33 in energizing also completes a circuit at its front contact and outer armature for slow-to-operate relay 35. Relay 35 in operating disconnects battery from impulse sender S, and is made slow-to-operate so that the connecting relay 39 in the trunk circuithas an opportunity to operate and lockup. before the battery is disconnected therefrom. .On its return to normal, impulse sender S interrupts the loop leading to the automatic exchange in accordance with the digits dialed and serves to operate the switches at the automatic exchange in After the necessary operation of the impulse sender to cause the establishment of a connection between the subscriber of the calling line A and the called line G, the operator restores key 24 to normal, whereupon relays-33, 35 and 25 are released. Relay 25 in releasing restores the continuity of the cord circuit, thereby extending the line of supervisory signal 21.

calling station A of the manualexchangeto the line of the called station Grat the automatic exchange. The callingsubscriber is now supplied'with talking battery from the automatic exchange over a path which may be traced as follows: grounded battery, lefthand winding ofrelay 52, of the connector, terminal 60, brush 58, brush 56, terminal 54, inner right-hand armature and front contact of relay 39, rings of'jack 31 and plug 30, inner normal contacts of relay 25, winding of relay 20, lower normal contacts of ringing key 4, rings of plug 8 and jack 7 through the sub-station loop, tips of jack 7 and. plug 8, upper normal contacts of ringing key 4, outer normal contacts of relay 25, tips of plug 30 and jack 31, front contact and outer right-hand armature of relay 39, terminal 53, brush 55, brush 57, terminal59, and right-hand winding of relay 52 to ground. 7

Upon completion of conversation and restoration of the receiver to the switch hook at station A, supervisory relay 20 will deenergize thereby establishing the circuit for The operator observing this signal removes plugs 8 and 30 from their associated jacks. The removal of plug 30 from jack 31 causes the sleeve relay 32 to release which in turn releases relay 39.

Removal of plug 30 from jack 31 interrupts V the bridge across the trunk circuit C leading to the automatic exchange, thereby restoring the switches to normal in the well known manner.

Trunk circuit C is shownras a two-way trunk circuit. Abrief description of the operation of an incoming call over trunk circuit C will be given- Assuming that ringing current is projected over'connector bank terminals 66 and 67, which are multipled to the line finder terminals 53 and 54, from a source of ringing current (not shown) at an automatic exchange, relay 61 of the trunk circuit will be energized and in operating will light a trunk signal 62 for indicating to the operator that a call has arrived and complete a circuit for operating relay 39 to render the talking conductors of the trunk circuit continuous. The circuit over which relay 61 is actuated may be traced as follows; a source of ringing current (not shown), terminal 66, condenser 64, right-hand winding of relay 61, back contact and outer armature of relay 32, terminal 67 'tothe source of ringing current. Belay61,

grounded battery, inner normal contacts of relay 32, outer armature and front contact of relay 61, inner armature of relay 61, and front contact of the inner armature, resistance 63, and trunk signal 62 to ground. The circuit for operating relay 39 extends from grounded battery through the inner normal contacts of relay 32, front contact and outer armature of relay 61 and right-hand winding of relay 39 to ground.

The operator, observing the trunk signal 62, inserts plug 30 into jack 31, whereupon.

a circuit for sleeve relay 32 is completed over a path previously traced. Relay 32, in operating, opens the locking circuits for trunk signal 62 and relay 61, and at its alternate contact completes a circuit for maintaining relay 39 energized. The circuit for maintaining relay 39 energized may be traced as follows: ground, left-hand Winding of relay 39, left-hand alternate contacts of relay 39, and alternate contacts of relay 32 to grounded battery. The operator then actuates listening key 9 and inquires the wants of the calling subscriber. Assuming subscriber A at the manual exchange is desired, the operator inserts plug 8 into jack 7 and actuates key 4 to signal station A. The subscriber at station A, in responding to the signal, removes the receiver from the switch-hook, thereby closing a circuit for supervisory relay 20, which, in energizing, extinguishes the supervisory lamp 21- in the manner wellknown, thus indicating to the operator that the called subscriber has answered. Upon the replacement of the receiver, supervisory lamp 21 will again light, whereupon the operator will remove plugs 30and 8 from their asociated jacks which will restore all apparatus to normal and the system is ready for the next call.

It will be noted from the above description that, on outgoing calls to the automatic exchange by maintaining the conductors extending from the manual to the automatic exchange open, until the impulse sender is operated, it is impossible through any manipulation of the plug 30 or successive 1nsertions of the plug 30 into jack 31 to cause the false operation of the switching apparatus at the automatic exchange, thereby preventing a false selection.

\Vhat is claimed is:

1. In a telephone exchange system, in combination, a trunk circuit including a pair of normally open talking conductors, automatic switching apparatus accessible to one end thereof, a link circuit for connection with the other end thereof, an impulse sender associated with the link circuit, and means controlled by the impulse sender for closing the talking conductors of the trunk after the link circuit is connected therewith.

2. In a telephone exchange system, in combination, a trunk circuitincluding a pair of normally open talking conductors, a link circuit connected therewith, an impulse sender, means for connecting the impulse sender with the link circuit, and electromagnetic means for closing the normally open talking conductors operating in response to the initial actuation of the impulse sender.

3. In a telephone exchange system, in combination, a trunk circuit including a pair of normally open talking conductors, a link circuit connected therewith, an impulse sender, means for connecting the impulse sender with the link circuit, a relay adapted upon actuation to close the normally open talking conductors, means controlled by the impulse sender for actuating the relay, and a locking circuit for the relay completed upon actuation.

4. In a telephone exchange system, in combination, a trunk circuit including a pair of normally open talking conductors, a link circuit connected therewith, an impulse sender havingolf-normal contacts, means for connecting the impulse sender with the link circuit, a relay adapted upon actuation to close said talking conductors. and a circuit for actuating said relay, said circuit including said off-normal contacts.

5. In a telephone exchange system, a trunk circuit including a pair of normally open talking conductors, a link circuit, a relay in said trunk circuit operating upon connection of the link circuit with the trunk circuit. an impulse sender, means 'for connecting the impulse sender with the link circuit, a second relay connected to the trunk circuit adapted upon actuation to close the talking conductors, a circuit for actuating said second relay completed upon the actuation of said impulse sender, and means whereby said circuit is opened upon actuation of said second relay and a locking circuit controlled by said first relay is substituted therefor to maintain said second relay energized.

6. In a telephone exchange system, in combination, a trunk circuit including a pair of normally open talking conductors. automatic switches accessible to said trunk circuit, a link circuit connected therewith, an impulse sender having a forward and backward movement, means for connecting the impulse sender with the link circuit, av re lay in the trunk circuit energized in response to the forward movement of the impulse sender for closing the talking conductors. a locking circuit for the relay completed upon energization. and means responsive to the backward movement of the im pulse sender for operating the automatic switches.

7. A telephone system comprising a trunk circuit including a pair of normally open talking conductors extending from a first to a second central ollice, a telephone line terminating at the second central office, switching apparatus thereat controlled over the talking conductors from the first cent al oflice for establishing connection between the trunk circuit and the telephone line, a

link circuit at the first central ofiice, an impulse sender associated with the link circuit for operating the switching apparatus, means for connecting the impulse sender to the link circuit, electromagnetic means operated upon the initial actuation of the impulse sender for closing the normally open talking conductors, and a locking circuit completed upon operation of said electromagnetic means for maintaining the electromagnetic means in an operative condition.

8. In a telephone exchange system, atrunk circuit including normally open talking conductors and a third conductor, said talking conductors extending from a first to a second central oifice,atelephone line terminating at the second central office, automatic switches thereat for establishing connection between the trunk circuit and the telephone line, a link circuit at the first central oflice, an impulse sender, means for connecting the impulse'sender to the link circuit, a relay inche third conductor of the trunk circuit responsive to the connection of the link circuit with the trunk circuit, a second relay energized over a portion of the talking conductors of the engaged link and trunk circuit in response to the actuation of the impulse sender for closing the normally open talking conductors, and a locking circuit for the second relay controlled by the relay in the third conductor.

9. In a telephone system comprising a trunk circuit including a pair of normally open talkingconductors and a third conductor, said talking conductors extending from a manual to an automatic exchange, a telephone line terminating at the automatic exchange, automatic switches thereat controlled over the talking conductors from the manual oiiice for establishing connection between the trunk circuit and the telephone line, a link circuit at the manual exchange, an impulse sender at the manual exchange, means for connecting the impulse sender to the link circuit, arelay operating over the third conductor of the trunk and link circuits upon connection of the link circuit: with the trunk circuit, a second relay for closing the normally open talking conductors, said relay being operated in response to the actuation of the impulse sender, and a locking circuit for the second relay established 'upon energization, said circuit including a Contact of the first mentioned relay.

It). In a telephone exchange system, a trunk circuit including a pair of normally open talking conductors and a third conductor, said talking conductors extending from a first to a second oh'ice, a link circuit at the first central ofiice, an impulse sender, means over the'talking conductors for establishing connection between the trunk circuit andthe telephone line, a'relay. operated over a portion of the talking conductors of the link' and trunk circuits by the impulse sender when the link circuit is connected with the trunk circuit to close the normally open talking conductors, a sleeve relay in: the third conductor of the trunk circuit, and a locking circuit controlled bythe sleeve relay for maintaining the first mentioned relay operated. r 7

11. In a telephone exchange system, an automatic exchange, a manual'exchange, a twoway trunk having a pair of normally open talking conductors, extending between said exchanges, signaling current responsive means associated with-said trunk circuit at said manual exchange opera-ted inresponse to incoming calls from said automatic exchange, means including an impulse sender at said manual exchange for controlling switches at said automatic exchange on outgoing calls from said manual exchange, and

electromagnetic means at said 'manualexchange operating. in r'esponse'to the actuation of said signaling current responsive means or said impulse sender, depending on whether the call 1S mcomingor outgoing, to

close said normally open talking conductors. 1

12-. In a telephone exchange system, an automatic exchange, a manual exchange, a two-way trunk circuit having a pair of normally open talking conductors extending between said exchanges, an alternatingcurrent relay associated with said trunk circuit at said manual office operating in response to incoming calls from said automatic exchange, means including an impulse sender at said manual exchange for controlling switches at said-automatic exchange on outgoing calls trom said manual exchange, and a relay at said'manual oflice operating in response to the actuation of said alternating current relay or saidimpulse sender, de pending on whether the'callis incoming or outgoing, to close said normally open talking conductors. l 9 r 13. In a telephone exchange system,an automatic'exchange, a manual exchange, a two-way trunk circuithaving a'pair of normally open talking conductors extending between said exchanges, an alternating current relay associated with said trunk circuit at said manual oitice operating in response toincoming calls from said automatic exchange, means including an'impulse sender at-said manual exchange-for controlling switches at said automatic exchange onoutrelay at said manual oflice operating in response to the actuation of said alternating current relay or said impulse sender, depending on Whether the call is incoming or outgoing, to close said normally open talking conductors, a locking circuit for said relay completed upon actuation, and means for disconnecting said alternating current relay and said second mentioned relay during the establishment of a connection over said 10 trunk circuit.

ARTHUR RAYNSFORD. 

